What will the world look like after the bombs fall? Can God exist in a place without hope? When man's desire to survive overrides his morality, is the empire he constructs worth saving?

Those are some of the questions raised by Metro: Last Light. The (cheery!) first-person shooter is Russian studio 4A Games' follow-up to their flawed 2010 gem, Metro 2033. The Metro games are based on the works of author Dmitry Glukhovsky; the first game was based on his novel of the same name, and while the sequel isn't based on a specific work, it directly carries on the first game's storyline.

The Metro series is set some years after nuclear war has ruined the surface of the Earth and put an end to civilization as we know it. In Russia, survivors have retreated to the Metro, re-forging a bleak semi-existence in the tunnels beneath the city. This is the sort of game that mentions, in its opening cinematic, the very real possibility that God is dead.

Like Metro 2033, Last Light tells the story of a soldier named Artyom. The tale stands on its own, though it does assume a fair amount of knowledge of the conflict at the heart of the first game. That conflict centers around the mysterious "Dark Ones," freaky-looking humanoid beings who possess psychic powers and terrify the human denizens of the Metro. Last Light assumes that players got the "bad ending" in Metro 2033 and took the option to blast the entire population of Dark Ones into oblivion. The subsequent discovery of a single surviving Dark One sets the plot of Last Light in motion.

What follows is a breathless, well-paced and, aside from a handful of moral choices that affect the story's outcome, resolutely linear single-player story that has Artyom touring the lair of the fascistic Fourth Reich, a compound staffed by a powerful Communist army, and working his way through all manner of spooky catacombs, caves, and numerous jaunts to the surface.

The peaks and troughs of the narrative have been organized with a great deal of care; the story shifts between non-combat exploration, stealth, all-out firefights, and horror-tinged monster fighting with ease. One moment you'll find yourself in a factory taking on squads of well-armed soldiers, and shortly afterward you'll be alone in a swamp, facing off against horrible crab-monsters. 4A seems to have taken notes from Half-Life 2 in a number of places; while there aren't any puzzles to solve, the game's pacing often recalls Valve's 2004 masterpiece. The mostly surdy story only truly falters in the final act, where a series of revelations stack on top of one another so quickly that vital plot points go half-mentioned and it's easy to lose track of what's going on.

As they did in Metro 2033, 4A regularly demonstrates an uncanny mastery of the alchemy of atmosphere. Underground cities bustle and radiate with wretched life, and each location has been crafted with a rare degree of detail. There's not much to do in most cities, aside from stopping off to refill your ammunition and maybe customize one of your weapons, but I found myself regularly sidetracked, listening to traders talk about their most recent sorties, or soldiers telling grim tales of survival.

When in the field, you can carry three guns at a time, along with a varied arsenal of throwing knives, grenades, and other survival equipment. Weapons come in the usual variety of assault rifles, shotguns, sniper rifles and pistols, with a few variations. Each weapon can be upgraded with silencers, scopes, sights and stocks, though I found little reason to deviate beyond my standard silenced pistol/shotgun/assault rifle setup.

That said, the weapons in Last Light are all assembled with an uncommon attention to detail, and each one feels and sounds distinctive and memorable. I particularly liked my quick-fire shotgun, which held a revolver-like ring of shells close to the stock, which Artyom would replace one by one after he fired. And, hooray, the show-stealing "Bastard" submachine gun from Metro 2033 returns, chewing through its lateral-feed magazine in the same way my father eats corn on the cob.

Two of Metro 2033's other most distinctive elements make a welcome return in Last Light: The gas mask, and bullet-based currency. At many moments throughout the campaign, Artyom will have to don a gas mask, either to survive on the toxic surface or to stay alive inside a gas-filled chamber. It's a wonderfully claustrophobic thing, that gas mask—Artyom's watch displays how much time remains on his current filter, and to keep him from suffocating, you'll have to regularly change it. As his filter degrades, Artyom's breathing becomes increasingly ragged. I often found that even though I knew I had a minute or more left, I'd swap my filter just to give the poor guy a break.

Instead of coins or bills, the people of the Metro use military-grade ammunition as currency. These bullets are kept separate from your "everyday use" ammo and can be spent to buy weapon upgrades. However, if you're facing off against a dangerous enemy and need more firepower, you can opt to load up a clip of money-bullets and attack for more damage. Woe is you, standing there, firing a clip of money into an enemy, praying it dies quickly. You may wind up broke, but you'll live.

On Normal difficulty, I found that I almost never ran out of standard ammunition, but in my limited time with the harder difficulty setting, ammo was much rarer. Hardcore Metro fans will probably want to play this game on its hardest difficult first, saving the extra-hardcore "Ranger Mode" for a second playthrough. (I did not have Ranger Mode unlocked on my PC build of the game, so I haven't had a chance to try it out.)

For all its careful pacing and wonderful atmosphere, Last Light certainly has its share of problems. The enemy artificial intelligence is a few steps shy of where it would need to be to be truly enjoyable; enemies routinely failed to notice when I'd kill their nearby friends, and more than once I'd come upon an alerted foe walking into a corner without taking any kind of understandable action.

The animals and beasts you'll fight are even less nuanced, and usually just charge at you in a straight line. Nevertheless, the mutant monsters can make for some enjoyable showdowns, but they can also become tiresome. There are a few boss battles that are equally unsatisfying; you're mostly pitted against giant charging bullet-sponges with weak spots, and even one rampaging beast that must be tricked into bringing down a series of columns in a room. At those moments, the artifice of Last Light shows through the clearest.

While the locations in the game have been crafted with a fine eye for detail, the characters themselves feel half-formed. You'll regularly watch waxen humans talk, slowly turning their unmoving faces toward and away from you like animatronic figures. Last Light is a real testament to the power of good lighting and environmental design: The graphical fidelity of the world can be remarkably convincing, which stands in sharp contrast to how stilted and unconvincing the characters themselves can be.

Children, in particular, are a bit freakish, and their voice acting is hollow and odd; not a new problem for a video game to have, but certainly one that Last Light doesn't solve. If I'd passed through each area without stopping, I wouldn't have noticed the seams so often. But the game encourages players to stop and listen in to conversations, which often go on for minutes on end. And so you'll stand, watching as characters stand stock still with only their lips moving, zoning out as you listen to their (usually quite interesting!) conversations.

Life in the Metro isn't a holiday for the fairer sex, and neither is Metro: Last Light. This is a world filled with men and sexual violence, and almost every female character is either a prostitute, a stripper, or a potential rape victim. I don't mean to suggest that a post-apocalyptic underground society wouldn't reveal this sort of barbarism, but the game doesn't handle any of it particularly deftly.

One of the only exceptions to the prostitute/stripper/victim-rule is a female sniper who eventually becomes a love interest, in a rushed storyline that culminates in a stilted first-person lovemaking scene. (Aside from the frequent loading screens, Artyom never actually talks, so any potential for warmth is immediately torpedoed by his creepy silence.) The scene felt jarring, as did an earlier lap dance from a dead-eyed stripper that had me peering through my fingers in mortification.

Late in the game, a character remarks that "The Metro is a living, breathing thing, with a heartbeat, a soul, and a mind." Indeed, this place feels alive; sometimes more so than the men and women who occupy its tunnels.

In fact, Last Light is often at its best when there's no one else around. The psychic powers of the Dark Ones play into a running current of mysticism that makes Last Light's Moscow a more mysterious, spiritual place than your average ruined city. The whispers of the dead will call out to you, and scenes of horror and beauty will float up from the past, almost as though the city is still crying out in agony. These moments are chilling, and were easily my favorite parts of the game.

So now comes the big caveat: Technical performance. I played a PC review build of Last Light provided by the game's publisher, Deep Silver. Throughout the game, there's often an underlying feeling that Last Light hasn't been stitched together quite right. Granted, I was playing a pre-release build, but it crashed on me a number of times, usually forcing a complete reboot. In one instance, I encountered a bug where upon dying, I reloaded outside a door with no way to move or put on my gas mask. I had to either watch Artyom asphyxiate over and over or restart the entire chapter and lose twenty minutes of progress. Triggered events are often cued sloppily or out of sync, directional audio can be jumpy, and the game even hard-locked on me during the closing credits. One additional technical shortcoming that, while not a bug, remains annoying: The game appears to have only one save-slot, and when I started a new game on the higher difficulty, it erased all of my progress and left me unable to load any later chapters. A single save slot, in a PC game? What on earth?

Last Light's PC performance issues are perhaps more troublesome. I was having some fairly intense issues running the game on an AMD Radeon 6870 (with 8GB of RAM and an i5 3.4Ghz processor), and found that it ran much more smoothly on my other PC, which runs an Nvidia GeForce 660Ti (with 8GB of RAM and a i5 2.8Ghz). That said, I couldn't get either machine to run the game well on my TV through HDMI; both games seemed stuck at 24-30 frames per second, no matter which settings or resolutions I chose. The only way to get them to run at a high framerate was to plug them into my PC monitor via DVI.

Late last week, PR advised reviewers to turn off PhysX on AMD cards, which does help performance, but the game still feels substantially less optimized for AMD machines. (Last Light carries the endorsement and branding of Nvidia, the company who make GeForce cards, but not of AMD.) On an AMD 6870, it'd generally run at High-to-Very High settings and keep at 40-60FPS, but often it would dip into the nether regions below 20FPS. On my GeForce card, however, it ran the same settings in a 45-60FPS sweet spot for the majority of the game, and only occasionally dipped down to 30.

I don't have either console copy of Last Light, but Chris in the New York office has been testing out the 360 version and reports that it works for the most part, though it has crashed on him once. And, not to freak anyone out, but fellow Kotaku editor Luke Plunkett played the game on an AMD 6950 and it fried his card after about 15 minutes of playtime. His video card is now unusable. His card was broken all weekend, and he only just got it working again. Did the game cause that, or something else? There are too many variables to say for sure. I have yet to see anyone else report anything like that, at least.

I don't feel I have enough information to say anything definitive about the game's PC performance, so I'll keep an eye on forums once the game is out and there's a larger sample-size of players. But what I can say definitively is that while Last Light mostly worked fine on my GeForce-based PC, this game has a few more technical problems than it ought to.

I've been emailing with Deep Silver PR about Last Light's performance issues, though I don't yet have any official word on a patch or any planned fixes. I've also reached out to AMD to ask if they're going to issue new drivers. I'll update once I know more. For the time being, if you can bear to wait, I'd recommend holding off on Last Light if you're using an AMD graphics card, as the game will hopefully get more playable in the near future. And hey, there's already a Last Light-optimized beta driver out for GeForce cards, which I haven't tested but which Nvidia claims further improves performance.

Despite those technical irritations, I very much enjoyed the majority of my time with Metro: Last Light. (Oh, the power of well-wrought atmosphere!) It's a game of stark, nightmarish beauty, and while it borrows liberally from many other games—among them S.T.A.L.K.E.R., Half-Life 2, Far Cry 2 and its own predecessor—Last Light still manages to forge a weighty, worthy identity of its own.